Instructions to pin screen on BSNL devices

How to protect your privacy when lending a BSNL smartphone or tablet to someone else. Instructions for setting up "screen pinning" on a BSNL brand device. Block an application on the screen from which the user will not be able to exit without knowing the unlock pin, in this way you will prevent them from seeing your messages, photos and private data that you do not want to show.

BSNL Champion Penta PS650 BSNL Champion Penta PS650
BSNL Champion SM3512 BSNL Champion SM3512
BSNL Champion PS501 BSNL Champion PS501